Under oil expulsion fuses are generally used in high voltage systems to protect the electric devices from fault currents. The expulsion fuse is ideally suited for use in series with backup current limiting fuses since it can be used to provide current interruption under low fault conditions without operation of the more costly limiting fuse. Low fault current clearing had until now to some extent been limited by the absence of controlled pressures within the expulsion fuse as described in my copending application Ser. No. 134,966 entitled "High Current Under Oil Expulsion Fuse", now U.S. Pat. No. 4,320,375. Fault current clearing in all current ranges has also been limited by the inability to dissipate the energy imparted to the fuse element assembly and its surrounding tubular support assembly.